Generally, except a one piece solid golf ball, a golf ball is formed of a multilayer structure in which a core is directly disposed or one or more intermediate layers are disposed in addition thereto and a cover surrounds the core.
In the case of such golf ball having the multilayer structure as described above, when the cover or the intermediate layer is formed of a thermoplastic material such as ionomor resin and thermoplastic elastomer, the cover or intermediate layers may be generally manufactured by injection molding.
In manufacturing a golf ball having a multilayer structure, a process of forming a cover may be easily performed by well-known injection molding. On the other hand, a general method of forming a core layer of a multilayer structure including one or more intermediate layers is performed by forming and taking out an uncross-linked outer core layer hemisphere by using a first press process, manually disposing an inner core layer in a corresponding hemisphere, and then cross-linking the output core layer hemisphere with the inner core layer by using a second press process.
However, in the case of such general method, since a process thereof is complicated, productivity is decreased. On the other hand, since it is difficult to maintain a uniform interval between the outer core layer and the inner core layer forming the intermediate layer, the quality of the golf ball is deteriorated.